Guide rail assembly for pusher-type furnace

ABSTRACT

PORTED ON THE RAIL EITHER THROUGH THE INTERMEDIARY OF THESE SPACERS OR THROUGH LATERAL RAIL EXTENSIONS ON WHICH THE FLANGES REST.   TO SUPPORT A SUCCESSION OF WORKPIECES ON A COOLED GUIDE RAIL OF A PUSHER-TYPE FURNACE, CARRIER BLOCKS WITH HOLLOW PROFILES AND DOWNWARDLY DIVERGING SIDE FLANGES ARE INTERPOSED BETWEEN THE WORKPIECES AND THE RAIL, THE FLANGES BRACKETING THE UPPER PART OF THE RAIL WITH LATERAL CLEARANCE TO ACT AS HEAT SHIELDS THEREFOR. THERMALLY INSULATING SPACERS OCCUPY PART OF THE HOLLOW CROSS SECTIONS OF THE BLOCKS, THE LATTER BEING SUP-

United States Patent lnventors Appl. No. Filed Patented AssigneePriority GUIDE RAIL ASSEMBLY FOR PUSHER-TYPE FURNACE ll-hns WemeckOberhaueen; Edgar Latnrell, 0herh.-Sterkrade, Germany Aug. 5, 1968 June28, 1971 Huttenwerk Oberhausen AG P115 83 363.3andP 15 83 344.4

12 Claims, 10 DrnwlngFlgs.

US. Cl......

Int. Cl.

Field of Search 263/6, 6 (B); 148/155, 157; 2l4/(lnquired) ReferencesCited UNITED STATES PATENTS 3/1906 Miller 4/1965 Boutigny et a1. 10/1965Molz 4/1966 Loeck et a1.

FOREIGN PATENTS 2/1953 Belgium 5/1962 France 12/1960 Germany PrimaryExaminerJ. Spencer Overholser Assistant ExaminerR. Spencer AnnearAnomeyl(arl F. Ross ABSTRACT: To support a succession of workpieces on acooled guide rail of a pusher-type furnace, carrier blocks with hollowprofiles and downwardly diverging side flanges are interposed betweenthe workpieces and the rail, the flanges bracketing the upper part ofthe rail with lateral clearance to act as heat shields therefor.Thermally insulating spacers occupy part of the hollow cross sections ofthe blocks, the latter being supported on the rail either through theintermediary of these spacers or through lateral rail extensions onwhich the flanges rest.

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GUIDE RAIL ASSEMBLY FOR PUSEIER-TYPE FURNACE Our present inventionrelates to a guide rail assembly for a pusher-type industrial furnace asdisclosed, for example, in commonly owned U.S. Pat. Nos. 3,245,672 and3,296,039 to K. Loeck et al. g

In a furnace of this type, designed for the heat treatment of metallicbodies such as steel billets, blooms or ingots, the workpieces aresupported on tubular, substantially horizontal rails, traversed by acooling fluid, through the intermediary of a series of heat-conductivecarrier blocks; in view of the high furnace temperatures, e.g. betweenl,250 and l,300 C these mounting blocks must be made of highlyheat-resistant metal, generally steel. The blocks should have arelatively large surface area exposed to the furnace atmosphere in orderto help equalize the temperature along the workpiece surface bydistributing the heat of an enveloping circulation of hot gases to theundersides of the workpieces in contact with the blocks. The proximityof the cooled rail, however, tends to develop so-called black stripes onthese undersides since some of the heat from the supported regions isconducted away toward the rail so that treatment is incomplete along thezone of contact; this is objectionable because of its detrimental effectupon subsequent processing stages in which, e.g. during rolling,differences in thickness may occur as a result of the nonuniformheating.

To minimize this conductive loss of heat from the supported workpieceportions, the carrier blocks were heretofore provided with relativelytall webs representing a path of restricted thermal conductivity. Thisconstruction, however, requires the use of substantial amounts ofexpensive heat-resistant metal and may also inconveniently increase therequired internal dimensions of the furnace. Furthermore, we have foundthat the exposed web surfaces tend to absorb thermal radiation from thenearest workpiece surfaces so as to act as heat sinks. The radiant heatso absorbed is directly transmitted to the rail and raises thetemperature of its cooling fluid which therefore must be circulated at afaster rate or cooled more intensely.

Thus, the general object of our present invention is to provide improvedsupporting means for workpieces traveling in the aforedescribed mannerfrom an inlet to an outlet of a furnace, with avoidance of theaforementioned drawbacks and reduction in the overall size of thecarrier blocks made from high-quality metal.

This object is realized, pursuant to our present invention, by a shapingof the carrier blocks with hollow profiles bounded by downwardlydiverging side flanges which bracket the upper part of the associatedguide rail with lateral clearance therefrom, the carrier blocks beingsupported on the rail with the aid of mounting means of limited thermalconductivity.

The aforementioned mounting means may include lateral extensions of therail and/or thermally insulating spacers inserted between the rail andthe tops of the hollow blocks. In the first instance, the railextensions may be web portions projecting from the outer rail surface,preferably in a horizontal midplane thereof, or may form part of a yokestraddling the rail. In the second instance the spacers may be ceramicmembers strong enough to sustain all or part of the load and flanked,advantageously, by lateral abutments formed by the flanges of the blocksor rising from the rail itself. The lateral flanges, which need not beintegral with the central part or head of the block, may also rest onbricks or the like secured to the underside of the rail and forming arefractory encasement for its lower part.

The invention will be described in greater detail with reference to theaccompanying drawing in which:

FIG. 1 is a vertical cross-sectional view of an industrial furnace ofthe general type described above and shown in the aforementioned Loecket al. patents;

FIG. 2 is an enlarged cross-sectional view of a guide rail and carrierblock according to the invention, forming part of the furnace of FIG. 1;

FIG. 3 is a view similar to FIG. 2, showing a modification;

FIG. 4 is a fragmentary side view (parts broken away) of the assembly ofFIG. 3;

FIG. 3 is another view similar to FIG. 2, showing a furthermodification;

FIG. 6 is a view similar to FIG. 4, relating to the assembly of FIG. 5;and

FIGS. 7-10 are still other cross-sectional viewssimilar to FIG. 2,representing additional embodiments.

In FIG. 1 we have shown an industrial furnace 1 of the type described inwhich two rows of billets 2 are pushed along two pairs of guide rails 3through the intermediary of carrier-block assemblies 8 as more fullydescribed hereinafter. The rails 3, of generally rectangular crosssection, are tubular and are connected to a source of cooling fluid, notshown, in the usual manner. The rails themselves are mounted viarefractory bricks 9, which encase their lower parts, on traverses 11(only one shown) supported by uprights 12. Ports 10 in a bulkhead l4serve for the circulation of a stream of hot gas below and above theworkpieces 2 as they travel over the rails 3 from an inlet to an outletof the furnace 1.

FIG. 2 shows details of the workpiece-supporting assembly 8 associatedwith each rail 3. This assembly includes a series of carrier blocks 4 ofgenerally prismatic profile, following one another in close successionalong the rail, and a yoke 5 (or a succession of such yokes) straddlingthe rail 3 by resting on a series of longitudinally spaced bosses 15thereof. A ceramic spacer bar 7, or a series of individual spacerblocks, is inserted between the tops of carrier blocks 4 and the yoke 5while leaving voids 16 on both sides along lateral flanges 6 which reston outrigger-type edge portions of the yoke. The refractory bricks 9,which may be made of the same material as the spacer member 7, can besecured to the underside of rail 3 in any convenient way not furtherillustrated and help balance the yoke 5 on the rail.

The carrier block 4 of heat-resistant steel is designed without anyhigh-rising central web so that the workpieces 2 pass at a relativelylow level above the rail 3. Nevertheless, the voids 16 and the thermallyinsulating spacer 7 minimize the flow of heat through the blocks 4toward the rail 3 whose only direct connection with the yoke 5 isthrough the spaced apart bosses 15. The lateral flanges 5 of block 4also act as radiation shields to prevent the transmission of radiantheat from the workpieces to the rail 3.

The assembly 8a of FIGS. 3 and 4 comprises a set of blocks 4a, similarto the blocks 4 of the preceding embodiment, whose flanges 60 rest onlaterally projecting lugs 5a of rail 3a which is here shown as a roundtube. The refractory encasement 90 has recesses receiving the lugs 5awhich, however, could also be extended into continuous webs overlyingthe edges of this encasement. Voids 16a on opposite sides of spacer 70again provide clearance between the flanges 6a and the rail 3a whoseonly heat-conductive connection with the blocks 4a is through the lugs5a.

FIGS. 5 and 6 show a tubular rail 3b split into lower and upper halves3b and 3b" which are separated by a throughgoing web 5b supporting theblocks 4b of assembly 8b. The arrangement is otherwise similar to thatof the preceding embodiment, with corresponding elements identified bysuffixes b in lieu of a. The web 5b is shown welded to the rail halves3b and 3b" at 17b.

In FIG. 7 we show a modified assembly which differs from assembly 8bonly by the more angular profile of its rail 3c and its blocks 40.Elements previously identified have been designated in FIG. 7 by thesame reference numerals followed by the sufiix c.

In FIG. 8, where the sufiix d is used to designate elements described inconnection with the preceding FIGS., the spacer 7d of assembly 8dsupports the block 4d whose flanges 6d also rest on the lower encasement9d. Ribs 19d rising from rail 3d form lateral abutments alongside thespacer 7d and hold it in position.

The assembly 8e of FIG. 9 differs from that of FIG. 8 by the fact thatthe flanges 6e of block 4e form lateral abutments l9e for the spacer 72,thus dispensing with the need for separate ribs integral with rail Se.

in the assembly 8f of H6. 10 we have shown a block having a generallytrapezoidal head 4f formed with bottom grooves to receive the top edgesof angularly bent strips (if, of the same heat-resistant steel as head4f, which play the part of the flanges 6, 6a, etc. shown in thepreceding FIGS. as integral parts of the respective blocks. The loweredges of the strips 6f rest on the refractory encasement 9f of rail 3f,since the lower edge portions of these strips are shielded against thefurnace atmosphere by adjoining ribs 21f of encasement 9f, they need notbe continuous but may be toothed or crenellated at 22f for furtherrestricting the direct heat exchange between the block 4f and the rail3f.

While we have described and illustrated a variety of ways in which ourpresent improvement can be carried into practice, it will be apparentthat other modifications are possible without departing from the spiritand scope of our invention as defined in the appended claims.

We claim:

1. In an industrial furnace having a heating chamber provided with atubular, substantially horizontal rail connected to be traversed by acooling fluid, said rail extending from an inlet to an outlet of saidchamber and being formed with lateral extensions, a row ofheat-resistant metallic carrier blocks on said rail for the support of aseries of workpieces to be heat-treated while passing throughsaidchamber, the improvement wherein said carrier blocks have a hollowprofile bounded by downwardly diverging side flanges which rest on saidextension and bracket the upper part of said rail with lateral clearancetherefrom, and thermally insulating spacer means inserted between saidrail and the tops of said blocks, said blocks having generallytrapezoidal heads formed with bottom slots alongside said spacer means,said flanges being angularly bent strips with upper edges received insaid slots.

2. In an industrial furnace having a heating chamber provided with atubular, substantially horizontal rail connected to be traversed by acooling fluid, said rail extending from an inlet to an outlet of saidchamber, and a row of heat-resistant metallic carrier blocks on saidrail for the support of a series of workpieces to be heat-treated whilepassing through said chamber, the improvement wherein said carrierblocks have a hollow profile bounded by downwardly diverging sideflanges which bracket the upper part of said rail with lateral clearancetherefrom, said rail being provided with mounting means of limitedthermal conductivity supporting said carrier blocks thereon, said railbeing further provided with lateral extensions forming part of saidmounting means, said flanges resting on said extensions.

3. The improvement defined in claim 2 wherein said extensions are webportions projecting from said rail substantially in a horizontalmidplane thereof.

4. The improvement defined in claim 2 wherein said extensions form partof a yoke straddling said rail.

5. The improvement defined in claim 4, further including thermallyinsulating spacer means inserted between said yoke and the tops of saidblocks.

6. The improvement defined in claim 3 wherein said mounting meansincludes thermally insulating spacer means inserted between said railand the tops of said blocks.

7. The improvement defined in claim 6 wherein said flanges form lateralabutments for said spacer means.

8. The improvement defined in claim 6 wherein said railis provided withupstanding ribs forming lateral abutments for said spacer means.

9. The improvement defined in claim 6 wherein said blocks have generallytrapezoidal heads formed with bottom slots alongside said spacer means,said flanges being angularly bent strips with upper edges received insaid slots.

10. In an industrial furnace having a heating chamber provided with atubular, substantially horizontal rail connected to be traversed by acooling fluid, said rail extending from an inlet to an outlet of saidchamber, and a row of heat-resistant metallic carrier blocks on saidrail for the support of a series of workpieces to be heat-treated whilepassing through said chamber, the improvement wherein said carrierblocks have a hollow profile bounded by downwardly diverging sideflanges which bracket the upper part of said rail with lateral clearancetherefrom, said rail being provided with mounting means of limitedthermal conductivity supporting said carrier blocks thereon, said railbeing further provided with a refractory encasement for its lower part,said flanges resting on said encasement.

Ill. The improvement defined in claim 10 wherein said en casement isprovided with upstanding ribs externally adjoining said flanges.

12. The improvement defined in claim 11 wherein said flanges havediscontinuous lower edges in the region of said ribs.

